Systems and methods for state context management in dual connectivity network environments

ABSTRACT

Devices, methods, and computer-readable media described herein and provide for sending, by a first wireless station, a suspend message to a wireless station associated with a radio resource control (RRC) session for a dual connectivity (DC) capable user equipment (UE) device that places the DC capable UE device in an RRC inactive mode; storing, by the first wireless station, UE context information from a core network for the DC capable UE device for the RRC session; and evaluating, by the first wireless station, a set of criteria to determine whether to also store the UE context information at the wireless station

RELATED APPLICATION

This patent application is a Continuation of U.S. Application 17/101,502filed on Nov. 23, 2020, titled “SYSTEMS AND METHODS FOR STATE CONTEXTMANAGEMENT IN DUAL CONNECTIVITY NETWORK ENVIRONMENTS,” the disclosure ofwhich is hereby incorporated by reference herein in its entirety.

BACKGROUND INFORMATION

Fifth Generation (5G) New Radio (NR) technology provides variousenhancements to wireless communications, such as flexible bandwidthallocation, improved spectral efficiency, ultra-reliable low-latencycommunications (URLLC), beamforming, high-frequency communication (e.g.,millimeter wave (mmWave)), as well as others. 5G systems supportmulti-radio dual connectivity (MR-DC) operations. For example, NR-NRdual-connectivity (NR-DC) involves simultaneous connections to both amaster 5G NR wireless station and at least one secondary 5G NR wirelessstation. In these non-standalone (NSA) 5G NR networks, the definedstates for the NR-DC UE include a Radio Resource Control (RRC) Inactivestate, in which the master node stores access stratum (AS) context ofthe UE, and controls whether the same AS context is also to be stored atthe secondary node.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary environment in which systems and methodsdescribed herein may be implemented;

FIG. 2 illustrates exemplary operating modes and allowed statetransitions for a 5G NR device of the environment of FIG. 1 ;

FIG. 3 illustrates an exemplary configuration of logic componentsincluded in one or more of the devices of FIG. 1 ;

FIG. 4 illustrates an exemplary configuration of logic componentsimplemented in the UE device of FIG. 1 ;

FIG. 5 illustrates an exemplary configuration of logic componentsimplemented in a wireless station of FIG. 1 ; and

FIG. 6 is a flow diagram illustrating processing by various componentsin the environment of FIG. 1 in accordance with an exemplaryimplementation.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The following detailed description refers to the accompanying drawings.The same reference numbers in different drawings may identify the sameor similar elements. Also, the following detailed description does notlimit the invention.

Implementations described herein relate to context state management foran MR-DC (e.g., NR-DC, etc.) device operating in defined modes andtransitioning therebetween in accordance with 5G NR protocols/standards.For example, in one implementation, an NR-DC device may, upon power-up,transition from an NR RRC idle mode or a disconnected (unregistered)state to an NR RRC connected mode with multiple 5G wireless stations atonce. The NR-DC device is allowed to connect to an “anchor” cell (alsoreferred to herein as master cell group (MCG)) associated with, forexample, one 5G radio access network (RAN), and at least one secondarycell (also referred to herein as secondary cell group (SCG)) associatedwith another 5G RAN, to access 5G services from a service providerduring an RRC session. The term “anchor cell,” as used herein, refers toa cell or channel associated with a master wireless station (or masternode).

In the NR RRC connected mode, NR-DC device context information is storedin both the master node and the secondary node. In an NR RRC inactivemode, the master node stores the NR-DC context information, and controlswhether the NR-DC information is also stored in the secondary node. Inimplementations described herein, the master node evaluates identifiedcriteria to determine whether to instruct the secondary node to storethe NR-DC context information.

FIG. 1 is a diagram of an exemplary environment 100 in which the systemsand methods described herein may be implemented. Referring to FIG. 1 ,environment 100 includes user equipment (UE) 110, a wireless station120-1 associated with a radio access network (RAN) 130-1, a wirelessstation 120-2 associated with a RAN 130-2, a core network 140 withnetwork devices 150-1 and 150-2, and a packet data network (PDN) 160.Wireless stations 120-1 and 120-2 may be referred to herein collectivelyas wireless stations 120 and individually as wireless station 120 or120-X, RANs 130-1 and 130-2 may be referred to herein collectively asRANs 130 and individually as RAN 130 or 130-X. Network devices 150-1 and150-2 may be referred to herein collectively as network devices 150 andindividually as network device 150 or 150-X. In other embodiments,environment 100 may include additional networks, fewer networks, and/ordifferent types of networks than those illustrated and described herein.

Environment 100 includes links between the networks and between thedevices. For example, environment 100 may include wired, optical, and/orwireless links among the devices and the networks illustrated. Acommunicative connection via a link may be direct and/or indirect. Forexample, an indirect communicative connection may involve anintermediary device and/or an intermediary network not illustrated inFIG. 1 . Additionally, the number and the arrangement of linksillustrated in environment 100 are exemplary. In the configurationillustrated in FIG. 1 , UE 110 may use wireless channels 170-1 and 170-2(referred to collectively as wireless channels 170) to access wirelessstations 120-1 and 120-2, respectively. Wireless channels 170 maycorrespond, for example, to a physical layer in accordance with 5G NRstandards (e.g., 3GPP-defined 5G air interfaces).

UE 110 (also referred to herein as UE device 110 or user device 110),may include any type of UE device having MR-DC mode capabilities (e.g.,NR-DC capabilities) and is able to communicate with different wirelessstations (e.g., wireless stations 120) using different wireless channels(e.g., channels 170) corresponding to different RANs (e.g., RANs 130-1and 130-2). UE 110 may be a mobile device that may include, for example,a cellular radiotelephone, a smart phone, a tablet, any type of internetprotocol (IP) communications device, a Voice over Internet Protocol(VoIP) device, a personal computer (PC), a laptop computer, a notebook,a netbook, a wearable computer (e.g., a wrist watch, headgear, eyeglasses, etc.), a gaming device, a navigation device, a media playingdevice, a digital camera that includes communication capabilities (e.g.,wireless communication mechanisms such as Wi-Fi), etc. In otherimplementations, UE 110 may be implemented as a machine-typecommunications (MTC) device, an Internet of Things (IoT) device, amachine-to-machine (M2M) device, etc.

UE 110 may connect to RANs 130 and other devices in environment 100 viaany conventional technique, such as wired, wireless, optical connectionsor a combination of these techniques. UE 110 and the user associatedwith UE 110 (e.g., the party holding or using UE 110) may be referred tocollectively as UE 110 in the description below.

According to implementations described herein, UE 110 may be provisioned(e.g., via a subscriber identity module (SIM) card or another secureelement) to recognize particular network identifiers (e.g., associatedwith RANs 130) and to support particular radio frequency (RF) spectrumranges (e.g., sub-6, mmWave, licensed, unlicensed, etc.).

Wireless stations 120 may each include a network device that hascomputational and wireless communication capabilities. Wireless stations120 may each include a transceiver system that connects UE device 110 toother components of RAN 130 and core network 140 using wireless/wiredinterfaces. Wireless stations 120 may be implemented as a base station(BS), a base transceiver station (BTS), a Node B, a next generation NodeB (gNode B), an evolved Node B (eNode B), an evolved LTE (eLTE) eNB, aremote radio head (RRH), an RRH and a baseband unit (BBU), a BBU, acentralized unit, a distributed unit (DU), or other type of wirelessnode, such as a small cell (e.g., a picocell node, a femtocell node, amicrocell node, etc.) that provides wireless access to RAN 130. Wirelessstations 120 may support RANs 130 that operate in the same or differentfrequency bands. For example, in one implementation, both RAN 130-1 andRAN 130-2 may include 5G NR RANs for 5G networks.

Core network 140 may include one or multiple networks of one or multipletypes. For example, core network 140 may be implemented to include aterrestrial network and/or a satellite network. According to anexemplary implementation, core network 140 includes a backhaul networkpertaining to multiple RANs 130. For example, core network 140 mayinclude a 5G network, a legacy network, etc.

Depending on the implementation, core network 140 may include variousnetwork elements that may be implemented in network devices 150. Suchnetwork elements may include a core access and mobility managementfunction (AMF), a user plane function (UPF), a session managementfunction (SMF), a unified data management (UDM), a policy controlfunction (PCF), a user data repository (UDR), an authentication serverfunction (AUSF) as well other network elements pertaining to variousnetwork-related functions, such as billing, security, authentication andauthorization, network polices, subscriber profiles, network slicing,and/or other network elements that facilitate the operation of corenetwork 140. In some implementations, wireless station 120-1 andwireless station 120-2 may directly interface with some network devices150-2 (e.g., UPF) for data plane communications and wireless station120-1 may directly interface with some network devices 150-1 (e.g., AMF)for control plane communications.

PDN 160 may include one or more networks, such as a local area network(LAN), a wide area network (WAN), a metropolitan area network (MAN), atelephone network, an application layer network, the Internet, etc.,capable of communicating with UE 110. In one implementation, PDN 160includes a network that provides data services (e.g., via packets or anyother Internet protocol (IP) datagrams) to UE 110.

The number and arrangement of devices in environment 100 are exemplary.According to other embodiments, environment 100 may include additionaldevices (e.g., thousands of UEs 110, hundreds of wireless stations 120,dozens of RANs 130, etc.) and/or differently arranged devices, thanthose illustrated in FIG. 1 .

As described above, in an exemplary implementation, UE 110 may be anNR-DC device capable of communicating via a 5G NR network. Inprovisioned systems based on current standards, UE 110 may connect to acell based on the signal strengths of the particular base stations.However, criteria other than signal strength may be used for selectingamong available cells.

Referring to FIG. 2 , existing 5G standards define RRC modes/statestransitions 200 for UE 110 with respect to RAN 130. At power up 205, UE110 may be unregistered with RAN 130, and may assume an RRC idle mode ordisconnected state 210. UE 110 may, upon attachment and registration 215via an RRC connection, transition to an RRC connected (active) mode 220.5G standards define a third state, an RRC (connected) inactive mode 230,to reduce the control plane latency, reduce signaling overhead, reducepower consumption, etc., while at the same time reduce an amount of timeto resume NR RRC connected mode 220. For example, periods of inactivityin RRC connected mode 220 result in the RRC session being suspended 225and UE 110 being transitioned to RRC inactive mode 230, in which UE 110is still registered and connected to RAN 130, unlike RRC idle mode 210where UE 110 is disconnected and deregistered from RAN 130. UE 110 maysubsequently transition from RRC inactive mode 230 back to RRC connectedmode 220 using an RRC resume 235 operation. If UE 110 experiences aconnection failure 245 while in RRC inactive mode 230, UE 110 maytransition to disconnected state 210. If UE 110 experiences a connectionfailure 255 while in RRC connected mode 220, UE 110 may transition todisconnected state 210. From RRC connected mode 220, UE 110 may detachvia an RRC release message 265 and transition to RRC idle mode ordisconnected state 210, for example, to conserve bandwidth and/or signalradio bearers (SRBs) and/or to end the RRC session. RRC modes and/orstate transitions other than what are depicted in FIG. 2 are possible.

Systems and methods described herein pertain to controlling the storageof UE context information for UE 110 in NR RRC inactive mode 230. In oneimplementation, a master node (e.g., wireless station 120-1) maydetermine the circumstances in which a secondary node (e.g., wirelessstation 120-2) is to store/not store context information for UE 110 whenUE 110 is in NR RRC inactive mode 230. In this manner, when theadvantages (e.g., improved RRC data session set-up time after transitionto NR RRC connected mode 220, etc.) of storing UE context information inthe secondary node outweigh the disadvantages (e.g., reduction oflimited memory space, etc.) the secondary node may store the UE contextinformation. In some implementations, the master node may evaluate, asfurther described below, predetermined criteria to determine alikelihood that the secondary node RRC connection will be maintainedafter UE 110 resumes NR RRC connected mode 220.

FIG. 3 illustrates an exemplary configuration of UE 110. Other devicesin environment 100, such as wireless stations 120, network devices 150and elements in PDN 160 may be configured in a similar manner. Referringto FIG. 3 , UE 110 may include bus 310, processor 320, a memory 330, aninput device 340, an output device 350 and a communication interface360. Bus 310 may include a path that permits communication among theelements of UE 110.

Processor 320 may include one or more processors, microprocessors, orprocessing logic that may interpret and execute instructions. Memory 330may include a random access memory (RAM) or another type of dynamicstorage device that may store information and instructions for executionby processor 320. Memory 330 may also include a read only memory (ROM)device or another type of static storage device that may store staticinformation and instructions for use by processor 320. Memory 330 mayfurther include a solid state drive (SDD). Memory 330 may also include amagnetic and/or optical recording medium (e.g., a hard disk) and itscorresponding drive.

Input device 340 may include a mechanism that permits a user to inputinformation to UE 110, such as a keyboard, a keypad, a mouse, a pen, amicrophone, a touch screen, voice recognition and/or biometricmechanisms, etc. Output device 350 may include a mechanism that outputsinformation to the user, including a display (e.g., a liquid crystaldisplay (LCD)), a printer, a speaker, etc. In some implementations, atouch screen display may act as both an input device and an outputdevice.

Communication interface 360 may include one or more transceivers that UE110 (or wireless station 120) uses to communicate with other devices viawired, wireless or optical mechanisms. For example, communicationinterface 360 may include one or more radio frequency (RF) transmitters,receivers and/or transceivers and one or more antennas for transmittingand receiving RF data via links 170. Communication interface 360 mayalso include a modem or an Ethernet interface to a LAN or othermechanisms for communicating with elements in a network, such as RAN 130or another network.

The exemplary configuration illustrated in FIG. 3 is provided forsimplicity. It should be understood that UE 110 (or wireless station120) may include more or fewer devices than illustrated in FIG. 3 . Inan exemplary implementation, UE 110 (or wireless station 120) mayperform operations in response to processor 320 executing sequences ofinstructions contained in a computer-readable medium, such as memory330. A computer-readable medium may be defined as a physical or logicalmemory device. The software instructions may be read into memory 330from another computer-readable medium (e.g., a hard disk drive (HDD),solid-state drive (SSD), etc.), or from another device via communicationinterface 360. Alternatively, hardwired circuitry may be used in placeof or in combination with software instructions to implement processesconsistent with the implementations described herein. Thus,implementations described herein are not limited to any specificcombination of hardware circuitry and software.

FIG. 4 is an exemplary functional block diagram of componentsimplemented in UE 110. In an exemplary implementation, all or some ofthe components illustrated in FIG. 4 may be implemented by processor 320executing software instructions stored in memory 330. In otherimplementations, all or some of the components illustrated in FIG. 4 maybe implemented in hardware or a combination of hardware, firmware andsoftware used to perform the functionality described below.

UE 110 may include cell monitoring logic 410, cell selection/switchinglogic 420 and communication logic 430. In alternative implementations,the components or a portion thereof may be located externally withrespect to UE 110.

Cell monitoring logic 410 may include logic to measure and/or monitorthe signal strengths of detected signals from associated cells. Forexample, UE 110 may measure the strength of communication signals fromeach of wireless stations 120.

Cell selection/switching logic 420 may include logic to select, based oninformation such as detected signal strengths from cell monitoring logic410, a cell, such as an anchor cell (e.g., MCG) or a non-anchor cell(e.g., SCG) in environment 100. For example, UE 110 illustrated in FIG.1 may establish communications with wireless station 120 associated witha cell (e.g., an anchor cell in this example) to access 5G NR services.For example, selecting a cell that corresponds to an anchor cell or MCGmay allow that anchor cell or MCG to setup dual connectivity (DC) togNBs (or SCGs) or other device (e.g., small cell) associated withcommunications via a 5G NR cell when UE 110 is located within a coveragearea of the 5G NR cell, as further described below. In oneimplementation, cell selection/switching logic 420 may include logic foron-demand switching of connectivity from a current 5G SCG to another 5GSCG anchored by a same 5G MCG (or a different 5G MCG) using layer 2signaling, for example, a media access control (MAC) control element(CE) associated with UE 110. In this manner, 5G (e.g., mmWave, sub-6,etc.) connectivity may be maintained, following UE 110’s movementbetween 5G SCGs or UE 110’s experiencing signal degradation (e.g.,obstruction) within a current 5G SCG at the air interface, withoutdisruption, as further described below.

Communication logic 430 may include logic to communicate with elementsin environment 100, directly or indirectly. For example, communicationlogic 430 may, based on instructions from cell selection/switching logic420, transmit and receive communications associated with establishing anRRC connection with appropriate wireless stations 120 in environment100, such as wireless station 120-1 associated with an MCG.Communication logic 430 may, based on instructions from cellselection/switching logic 420, also transmit and receive communicationsassociated with on-demand switching to establish a connection withwireless station 120-2 associated with an SCG.

Although FIG. 4 shows exemplary components of UE 110, in otherimplementations, UE 110 may include fewer components, differentcomponents, differently arranged components, or additional componentsthan depicted in FIG. 4 . In addition, functions described as beingperformed by one of the components in FIG. 4 may alternatively beperformed by another one or more of the components of UE 110. Further,any of wireless stations 120 may correspond to an MCG or an SCG.

FIG. 5 is an exemplary functional block diagram of componentsimplemented in wireless station 120. In an exemplary implementation, allor some of the components illustrated in FIG. 5 may be implemented byprocessor 320 executing software instructions stored in memory 330. Inother implementations, all or some of the components illustrated in FIG.5 may be implemented in hardware or a combination of hardware, firmwareand/or software used to perform the functionality described below.

Wireless station 120 may include MCG control logic 510, SCGconfiguration logic 520, handover control logic 530, and communicationlogic 540. In alternative implementations, the components or a portionthereof may be located externally with respect to wireless station 120.

MCG control logic 510 may include logic to generate and transmit/receivecontrol signaling to/from UE 110, which may be an NR-DC devicecommunicating via a 5G SCG (e.g., SgNB). For example, MCG control logic510 may provide anchoring operations and control plane signaling foreach 5G NR SCG in an SCG-set assigned to MCG (anchor cell).

SCG configuration logic 520 may include logic to configure a set of 5GNR cells anchored by a 5G MCG (e.g., an MgNB). For example, SCGconfiguration logic 520 may use RRC to configure multiple SCGs havingcoverage areas that at least partially overlap with a coverage area ofthe MCG.

RRC may correspond to a protocol that handles signaling between UE 110and RAN 130. RRC-defined modes (e.g., idle, connected, inactive, etc.)and allowed transitions may be handled by the control plane whichincludes an RRC layer. During RRC idle mode, for example, UE 110 maycamp on an MCG after MCG selection or reselection takes place, wherefactors such as, for example, radio link quality, cell status, and radioaccess technology may be considered. As used herein, “camping” on aselected MCG refers to UE 110 maintaining data exchanges with corenetwork 140 within the confines of the selected MCG (e.g., associatedwith one of wireless stations 120). A cell or MCG may include a coveragearea served by a gNB (e.g., one of wireless stations 120) using aparticular frequency band. Thus, in some cases, an MCG and wirelessstation 120 servicing the MCG may be referred to interchangeably.

UE 110 may also monitor a paging channel to detect incoming calls andacquire system information. In the RRC idle mode, the control planeprotocols include MCG selection and reselection procedures. During RRCconnected mode, UE 110 may provide the MCG with downlink channel qualityand neighbor cell information so the MCG may assist UE 110 to setup themost suitable SCGs for dual connectivity. For example, UE 110 maymeasure parameters (e.g., radio link signal strength) associated with acurrent set of SCGs to which UE 110 has dual connectivity, as well asthe neighboring SCGs. The key parameters (such as radio link signalstrength) of the SCG may be measured for the intra-frequency andinter-frequency neighboring SCGs. The measurements may be tracked anduploaded to the RRC layer, which makes control decisions on which SCGsUE 110 is configured to connect using dual connectivity. Accordingly,SCG fast selection may be based on a number of levels of criteria, whichmay include absolute priority, radio link quality, and/or SCGaccessibility, or any combination of the criteria, for example,according to relative weighted values that are configurable for one ormore of the criteria.

SCG configuration logic 520 may configure a secondary node to store UEcontext information in some instances and not to store the UE context inother instances, when UE 110 transitions to an RRC inactive mode.

Handover control logic 530, using control information from MCG controllogic 510 and/or configuration information from SCG configuration logic520, may include logic to facilitate a handover associated withcommunications from one cell to another cell. For example, handovercontrol logic 530 may handover communications from one 5G MCG to another5G MCG. Handover control logic 530 may also handover communications froma 5G MCG to a 5G NR SCG. Handover control logic 530 may also handovercommunications from a 5G NR SCG to another 5G NR SCG. For example, if UE110 is located in an area supporting 5G communications, handover controllogic 530 may transition or handoff communications associated withwireless station 120-1 to wireless station 120-2 in the 5G network. Theterm “handover” as used herein (also referred to herein as “handoff”)should be broadly construed as the process of transferring an RRCsession from one cell or channel to another cell or channel while thedata session is occurring and substantially without the loss orinterruption of service. In one implementation, in a standalone (SA)NR-NR DC architecture, handover control logic 530 may handovercommunications from a 5G MCG (e.g., sub-6) to a 5G NR SCG (e.g., mmWavecell).

Communication logic 540, using information from MCG control logic 510,SCG configuration logic 520, and/or handover control logic 530, mayinclude logic to communicate with elements in environment 100 directlyor indirectly. For example, communication logic 540 may communicate withUE 110 to establish an RRC connection. Communication logic 540 may alsoinitiate communications with another cell, such as another 5G MCG and/ora 5G SCG to allow an NR-DC UE 110 to communicate via a 5G network, asfurther described below.

FIG. 6 is flow diagram illustrating exemplary processing 600 associatedwith NR-DC UE 110 anchored to a 5G NR wireless station (e.g., 120-1) viaa 5G NR MCG (e.g., RAN 130-1) overlapping (or co-coverage) service areaswith a secondary 5G wireless station (e.g., 120-2) via 5G NR SCG (e.g.,RAN 130-2). Processing 600 may begin with wireless station 120-1determining that NR-DC UE 110 is an NR RRC _connected mode, and wirelessstation 120-1 and wireless station 120-2 storing UE context for UE 110(block 610). For example, wireless station 120-1 may receive UE contextinformation (e.g., access stratum) from network device 150 in corenetwork 140.

Processing 600 may further include UE 110 transitioning to NRRRC_inactive mode 130, and wireless station 120-1 storing UE context ofUE 110 (block 615). For example, wireless station 120-1 may send an NRRRC suspend message to UE 110. Wireless station 120-1 may controlwhether the UE context is also stored at wireless station 120-2. In oneimplementation, wireless station 120-1 may progressively evaluate, in aprioritized order, a number of criteria to make the determination.Wireless station 120- 1’s evaluation may include wireless station 120-1first determining whether a degree of mobility associated with UE 110exceeds a particular threshold, when UE mobility is the criterion havingtop priority (block 620). The determination may be based on any datarelated to the mobility of UE 110, for example, a record of handoverinstances over a period of time, which may be obtained by wirelessstation 120-1 from network device 150-1 responsive to a request fromwireless station 120-1 that identifies UE 110. If UE 110 does not exceedthe applicable mobility threshold (block 620— NO), then wireless station120-1 may message wireless station 120-2 requesting it to store the UEcontext for UE 110 (block 625). That is, wireless station may determinethat UE 110 is relatively stationary and likely to continue to be usedas a secondary node when UE 110 transitions back to NR RRC connectedmode 220, making it beneficial for wireless station to retain the UEcontext.

On the other hand, where UE 110’s mobile profile exceeds the applicablemobility threshold (block 620—YES)—indicating that UE 110 is likely tobe out of the coverage area of wireless station 120-2 when UE 110resumes an active connection—wireless station 120-1 may further evaluatewhether a device type determined for UE 110 is of a type for which asecondary node (e.g., wireless station 120-2) is to store the UE context(block 630). For example, subscription information associated with UE110 may be compared to a list device types that require a relativelyquick data session set-up response, for example, when UE 110 returns toNR RRC_connected mode 220. In one implementation, subscriptioninformation may include a radio access technology (RAT) frequencyselection priority (RFSP) index value, a service profile identifier(SPID), or other type of identifier indicating a device type, forexample, obtained from network device 150. If a determination is madethat UE 110 corresponds to a device type for which the UE context is tobe stored in the secondary node (block 630—YES), then wireless station120-1 may message wireless station 120-2 requesting storage of the UEcontext (block 625).

On the other hand, where UE 110 corresponds to a device type for whichthe UE context is not stored in the secondary node (block 630—NO), thenwireless station 120-1 may further evaluate whether a data traffic typeassociated with the NR RRC session is of a type for which a secondarynode (e.g., wireless station 120-2) is to store the UE context (block640). In one implementation, wireless station 12-1 may use data from theNR RRC service request to compare to a list device types that involverelatively less frequent communication (e.g., signaling). If the datatraffic is determined to be of a type for which UE context is to bestored at the secondary node (block 640—YES), then wireless station120-1 may message wireless station 120-2 requesting storage of the UEcontext (block 625).

On the other hand, where data traffic does not correspond to the type ofdata traffic for which the UE context is not stored in the secondarynode (block 640—NO), then wireless station 120-1 may further evaluatewhether a data traffic model associated with the wireless station 120-1and wireless station 120-2 pairing is one for which a secondary node(e.g., wireless station 120-2) is to store the UE context (block 650).For example, data may indicate that certain master node-secondarypairings are designated for storage of the UE context, while others arenot. In some instances, a master node, when paired with some secondarynodes, may call for storage of UE context in the secondary node, andwhen paired with other secondary nodes does not. If the immediateMCG-SCG pairing, for example, is designated for storage of the UEcontext (block 650—YES), then wireless station 120-1 may messagewireless station 120-2 requesting storage of the UE context (block 625).On the other hand, when the immediate MCG-SCG pairing, for example, isnot designated for storage of the UE context (block 650—NO), then the UEcontext is not stored in and/or deleted from wireless station 120-2 whenUE 110 is in NR RRC inactive mode 230 (block 660), and process 600 ends.A different number of criteria and/or other criteria, having prioritiesdifferent than those described, may be used to evaluate whether it ismore beneficial than not to store UE context in wireless station 120-2when UE 110 is in NR RRC inactive mode 230. For example, evaluationcriteria and prioritization may be trained by artificial intelligence(AI) and/or machine learning network device 150, and/or updated by aself-organizing network (SON) network device 150.

Referring to block 625, when wireless station 120-2 has been requestedto store the UE context, wireless station 120-2 may assess currentstorage space to determine whether memory is available to store the UEcontext (block 635). If wireless station 120-2 has sufficient memory(block 635—YES), then the UE context is stored at secondary wirelessstation 120-2 (block 665). On the other hand, if insufficient storage isavailable (block 635—NO), then process 600 may include wireless station120-2 identifying context currently being stored at wireless station120-2 that has an associated relative priority that is lower than theimmediate UE context (block 645). Wireless station 120-2 may release thelower priority context data (block 655) to free up memory for storingthe immediate UE context (block 665). Upon storing the UE context,wireless station 120-2 may initiate a timer for the storage of the UEcontext at wireless station 120-2 (block 675) which may be set to a timevalue based on, for example, instructions from network device 150. TheUE context is then stored until the time expires and then the UE contextis removed from wireless station 120-2 (block 685), and process 600ends.

Implementations described herein provide for 5G service continuity foran NR-DC device by configuring a set of SCGs to be anchored to a non-5GMCG, where only one of the SCGs is active at a time for providing mmWaveconnectivity to a UE. When the current 5G connectivity degrades due toUE movement or physical obstructions, the UE’s MAC CE may initiate anon-demand switch (layer 2) to another SCG in the set of SCGs anchored tothe MCG. In this manner, handover is made between SCGs without the needto tear down and re-establish an SCG, and thus eliminating disruption tocontinuous mmWave service. Moreover, this results in a comparativelylower signaling overhead than conventional handovers involvingsignaling-intensive RRC operations.

The foregoing description of exemplary implementations providesillustration and description, but is not intended to be exhaustive or tolimit the embodiments to the precise form disclosed. Modifications andvariations are possible in light of the above teachings or may beacquired from practice of the embodiments.

For example, features have been described above with respect tosecondary node-centric algorithm for determining whether storage of UEcontext at a master node and a secondary node results in a net-benefitfor an RRC session. In other implementations, the algorithm maycontemplate various scenarios in which a UE device transitions from theNR RRC inactive mode back to NR RRC connected mode, and for which itwould not be beneficial and/or efficient to store the UE context in thesecondary node. For example, once the UE returns to the connected mode,the master node may determine that dual connectivity is no longer needbecause of RRC coverage parameters. In this case, the UE context wouldhave been stored in the secondary node during the RRC inactive mode onlyto have to then be removed after the state transition. In anotherscenario, the master node may determine that dual connectivity needs tobe maintained, but that a different secondary node is to be used by theUE device for this purpose. In which case, the UE context would havebeen stored in the secondary node during the RRC inactive mode only tohave to then be handed over to the different secondary node after thestate transition. In yet another scenario, the UE device may make thestate transition under a different master node that is paired with adifferent secondary node. In which case, the UE context would have beenstored in the secondary node during the RRC inactive mode only to haveto then be handed over to the different secondary node after the statetransition. In still another scenario, the UE device may make the statetransition in a different RAN paging area corresponding to a differentmaster node and a different secondary node. In which case, the UEcontext would have been stored in the secondary node during the RRCinactive mode only to have to then be handed over to the differentsecondary node after the state transition. Other scenarios are possible.

Further, while series of acts have been described with respect to FIG. 6, the order of the acts and signal flows may be different in otherimplementations. Moreover, non-dependent acts may be implemented inparallel.

To the extent the aforementioned embodiments collect, store or employpersonal information of individuals, it should be understood that suchinformation shall be collected, stored and used in accordance with allapplicable laws concerning protection of personal information.Additionally, the collection, storage and use of such information may besubject to consent of the individual to such activity, for example,through well known “opt-in” or “opt-out” processes as may be appropriatefor the situation and type of information. Storage and use of personalinformation may be in an appropriately secure manner reflective of thetype of information, for example, through various encryption andanonymization techniques for particularly sensitive information.

It will be apparent that various features described above may beimplemented in many different forms of software, firmware, and hardwarein the implementations illustrated in the figures. The actual softwarecode or specialized control hardware used to implement the variousfeatures is not limiting. Thus, the operation and behavior of thefeatures were described without reference to the specific softwarecode - it being understood that one of ordinary skill in the art wouldbe able to design software and control hardware to implement the variousfeatures based on the description herein.

Further, certain portions of the invention may be implemented as “logic”that performs one or more functions. This logic may include hardware,such as one or more processors, microprocessor, application specificintegrated circuits, field programmable gate arrays or other processinglogic, software, or a combination of hardware and software.

In the preceding specification, various preferred embodiments have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe broader scope of the invention as set forth in the claims thatfollow. The specification and drawings are accordingly to be regarded inan illustrative rather than restrictive sense.

No element, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly described as such. Also, as used herein, thearticle “a” is intended to include one or more items. Further, thephrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

What is claimed is:
 1. A method, comprising: sending, by a firstwireless station, a suspend message to a second wireless station servinga radio resource control (RRC) session for a user equipment (UE) device;storing, by the first wireless station, UE device context informationfrom a core network for the RRC session; and evaluating, by the firstwireless station, a set of criteria for storing the UE device contextinformation at the second wireless station, wherein the evaluatingcomprises determining two or more of: a level of mobility for the UEdevice; a device type for the UE device; a data traffic type associatedwith the RRC session; or a data traffic model for a pairing of the firstwireless station and the second wireless station.
 2. The method of claim1, wherein the evaluating further comprises determining a likelihoodthat the second wireless station will maintain an RRC connection to theUE device following a state transition for the UE device, the methodfurther comprising: sending, based on the likelihood that the RRCconnection is to be maintained, a first message to the second wirelessstation to store the UE device context information; and sending, basedon the likelihood that the RRC connection is not to be maintained, asecond message to the second wireless station to not store the UE devicecontext information.
 3. The method of claim 2, wherein sending the firstmessage comprises sending a timer value indicating an amount of timeafter which the second wireless station is to no longer store the UEdevice context information.
 4. The method of claim 2, wherein, based onthe likelihood that the RRC connection is not to be maintained, themethod further comprising: establishing another RRC connection toanother wireless station; triggering a handover of the UE device contextinformation from the second wireless station to the other wirelessstation; and removing the RRC connection.
 5. The method of claim 2,wherein, based on the likelihood that the RRC connection is to bemaintained, the method further comprising: determining that the secondwireless station is in an overload condition; determining that a firstrelative priority associated with RRC session is greater than a secondrelative priority associated with another RRC session; and terminatingthe other RRC session.
 6. The method of claim 1, wherein the determiningfurther comprises at least one of: determining the level of mobilitybased on a record of handover times associated with the UE device;determining the device type based on subscription information from thecore network; determining the data traffic type based on a servicerequest associated with the RRC session; or determining the data trafficmodel based on a record of observed data traffic.
 7. The method of claim1, wherein the determining further successively comprises determining,according to a relative priority, the level of mobility, the devicetype, the data traffic type, or the data traffic model until adetermination is made of the likelihood that the RRC connection is to bemaintained or until each of the criteria has been evaluated.
 8. Adevice, comprising: a processor configured to: send a suspend message toa wireless station associated with a radio resource control (RRC)session for a user equipment (UE) device; store UE device contextinformation from a core network for the RRC session; and evaluate a setof criteria for further storing the UE device context information at thewireless station, wherein the evaluation comprises determining two ormore of: a level of mobility for the UE device; a device type for the UEdevice; a data traffic type associated with the RRC session; or a datatraffic model for a pairing of the wireless station and another wirelessstation.
 9. The device of claim 8, wherein to evaluate the set ofcriteria, the processor is further configured to determine a likelihoodthat the wireless station will maintain an RRC connection to the UEdevice following a state transition for the UE device, wherein theprocessor is further configured to: send, based on the likelihood thatthe RRC connection is to be maintained, a first message to the wirelessstation to store the UE device context information; and send, based onthe likelihood that the RRC connection is not to be maintained, a secondmessage to the wireless station to not store the UE device contextinformation.
 10. The device of claim 9, wherein to send the firstmessage, the processor is configured to send a timer value indicating anamount of time after which the wireless station is to no longer storethe UE context information.
 11. The device of claim 9, wherein, based onthe likelihood that the RRC connection is not to be maintained, theprocessor is further configured to: establish another RRC connection toa third wireless station; trigger a handover of the UE device contextinformation from the wireless station to the third wireless station; andremove the RRC connection.
 12. The device of claim 9, wherein, based onthe likelihood that the RRC connection is to be maintained, theprocessor is further configured to: determine that the wireless stationis in an overload condition; determine that a first relative priorityassociated with RRC session is greater than a second relative priorityassociated with another RRC session; and terminate the other RRCsession.
 13. The device of claim 8, wherein the processor is configuredto at least one of: determine the level of mobility based on a record ofhandover times associated with the UE device; determine the device typebased on subscription information from the core network; determine thedata traffic type based on a service request associated with the RRCsession; or determine the data traffic model based on a record ofobserved data traffic.
 14. The device of claim 8, wherein the processoris configured to successively determine, according to a relativepriority, the level of mobility, the device type, the data traffic type,or the data traffic model until the processor determines the likelihoodthat the RRC connection is to be maintained or until each of thecriteria has been evaluated.
 15. A non-transitory computer-readablemedium for storing instructions which, when executed by a processorassociated with a first wireless station, cause the processor to: send asuspend message to a second wireless station associated with a radioresource control (RRC) session for a user equipment (UE) device; storeUE device context information from a core network for the RRC session;and evaluate a set of criteria for storing the UE device contextinformation at the second wireless station, wherein the evaluationcomprises determining two or more of: a level of mobility for the UEdevice; a device type for the UE device; a data traffic type associatedwith the RRC session; or a data traffic model for a pairing of the firstwireless station and the second wireless station.
 16. The non-transitorycomputer-readable medium of claim 15, wherein to evaluate the set ofcriteria, the instructions cause the processor to determine a likelihoodthat the second wireless station will maintain an RRC connection to theUE device following a state transition for the UE device, wherein theinstructions further cause the processor: send, based on the likelihoodthat the RRC connection is to be maintained, a first message to thesecond wireless station to store the UE device context information; andsend, based on the likelihood that the RRC connection is not to bemaintained, a second message to the second wireless station to not storethe UE device context information.
 17. The non-transitorycomputer-readable medium of claim 16, wherein to send the first message,the instructions further cause the processor to: send a timer valueindicating an amount of time after which the second wireless station isto no longer store the UE context information.
 18. The non-transitorycomputer-readable medium of claim 16, wherein, based on the likelihoodthat the RRC connection is not to be maintained, the instructionsfurther cause the processor to: establish another RRC connection toanother wireless station; trigger a handover of the UE device contextinformation from the wireless station to the other wireless station; andremove the RRC connection.
 19. The non-transitory computer-readablemedium of claim 16, wherein, based on the likelihood that the RRCconnection is to be maintained, the instructions further cause theprocessor to: determine that the second wireless station is in anoverload condition; determine that a first relative priority associatedwith RRC session is greater than a second relative priority associatedwith another RRC session; and terminate the other RRC session.
 20. Thenon-transitory computer-readable medium of claim 15, wherein theinstructions further cause the processor to: determine the level ofmobility based on a record of handover times associated with the UEdevice; determine the device type based on subscription information fromthe core network; determine the data traffic type based on a servicerequest associated with the RRC session; or determine the data trafficmodel based on a record of observed data traffic.